diff --git a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
index e831b13915..62c25d5795 100644
--- a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
+++ b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
@@ -1373,6 +1373,10 @@ reset() {
        get_extension_func("glUniformMatrix4fv");
     _glValidateProgram = (PFNGLVALIDATEPROGRAMPROC)
        get_extension_func("glValidateProgram");
+    _glVertexAttrib4fv = (PFNGLVERTEXATTRIB4FVPROC)
+       get_extension_func("glVertexAttrib4fv");
+    _glVertexAttrib4dv = (PFNGLVERTEXATTRIB4DVPROC)
+       get_extension_func("glVertexAttrib4dv");
     _glVertexAttribPointer = (PFNGLVERTEXATTRIBPOINTERPROC)
        get_extension_func("glVertexAttribPointer");
 
@@ -1438,6 +1442,8 @@ reset() {
   _glUniformMatrix3fv = glUniformMatrix3fv;
   _glUniformMatrix4fv = glUniformMatrix4fv;
   _glValidateProgram = glValidateProgram;
+  _glVertexAttrib4fv = glVertexAttrib4fv;
+  _glVertexAttrib4dv = NULL;
   _glVertexAttribPointer = glVertexAttribPointer;
   _glVertexAttribIPointer = NULL;
   _glVertexAttribLPointer = NULL;
diff --git a/panda/src/glstuff/glGraphicsStateGuardian_src.h b/panda/src/glstuff/glGraphicsStateGuardian_src.h
index 0898dfe309..f9eaa36ccb 100644
--- a/panda/src/glstuff/glGraphicsStateGuardian_src.h
+++ b/panda/src/glstuff/glGraphicsStateGuardian_src.h
@@ -180,6 +180,8 @@ typedef void (APIENTRYP PFNGLUNIFORM4IVPROC) (GLint location, GLsizei count, con
 typedef void (APIENTRYP PFNGLUNIFORMMATRIX3FVPROC) (GLint location, GLsizei count, GLboolean transpose, const GLfloat *value);
 typedef void (APIENTRYP PFNGLUNIFORMMATRIX4FVPROC) (GLint location, GLsizei count, GLboolean transpose, const GLfloat *value);
 typedef void (APIENTRYP PFNGLVALIDATEPROGRAMPROC) (GLuint program);
+typedef void (APIENTRYP PFNGLVERTEXATTRIB4FVPROC) (GLuint index, const GLfloat *v);
+typedef void (APIENTRYP PFNGLVERTEXATTRIB4DVPROC) (GLuint index, const GLdouble *v);
 typedef void (APIENTRYP PFNGLVERTEXATTRIBPOINTERPROC) (GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *pointer);
 typedef void (APIENTRYP PFNGLVERTEXATTRIBIPOINTERPROC) (GLuint index, GLint size, GLenum type, GLsizei stride, const GLvoid *pointer);
 typedef void (APIENTRYP PFNGLVERTEXATTRIBLPOINTERPROC) (GLuint index, GLint size, GLenum type, GLsizei stride, const GLvoid *pointer);
@@ -833,6 +835,8 @@ public:
   PFNGLUNIFORMMATRIX3FVPROC _glUniformMatrix3fv;
   PFNGLUNIFORMMATRIX4FVPROC _glUniformMatrix4fv;
   PFNGLVALIDATEPROGRAMPROC _glValidateProgram;
+  PFNGLVERTEXATTRIB4FVPROC _glVertexAttrib4fv;
+  PFNGLVERTEXATTRIB4DVPROC _glVertexAttrib4dv;
   PFNGLVERTEXATTRIBPOINTERPROC _glVertexAttribPointer;
   PFNGLVERTEXATTRIBIPOINTERPROC _glVertexAttribIPointer;
   PFNGLVERTEXATTRIBLPOINTERPROC _glVertexAttribLPointer;
diff --git a/panda/src/glstuff/glShaderContext_src.cxx b/panda/src/glstuff/glShaderContext_src.cxx
index 87fafebb48..a6818f85de 100644
--- a/panda/src/glstuff/glShaderContext_src.cxx
+++ b/panda/src/glstuff/glShaderContext_src.cxx
@@ -197,6 +197,7 @@ CLP(ShaderContext)(CLP(GraphicsStateGuardian) *glgsg, Shader *s) : ShaderContext
   _glsl_program = 0;
   _uses_standard_vertex_arrays = false;
   _has_divisor = false;
+  _color_attrib_index = -1;
 
   nassertv(s->get_language() == Shader::SL_GLSL);
 
@@ -925,7 +926,7 @@ CLP(ShaderContext)(CLP(GraphicsStateGuardian) *glgsg, Shader *s) : ShaderContext
                        param_type == GL_UNSIGNED_INT_VEC3 ||
                        param_type == GL_UNSIGNED_INT_VEC4 ||
 #endif
-                       param_type == GL_UNSIGNED_INT );
+                       param_type == GL_UNSIGNED_INT);
 
       if (noprefix.empty()) {
         // Arbitrarily named attribute.
@@ -940,6 +941,9 @@ CLP(ShaderContext)(CLP(GraphicsStateGuardian) *glgsg, Shader *s) : ShaderContext
       } else if (noprefix == "Color") {
         bind._name = InternalName::get_color();
 
+        // Save the index, so we can apply special handling to this attrib.
+        _color_attrib_index = p;
+
       } else if (noprefix.substr(0, 7) == "Tangent") {
         bind._name = InternalName::get_tangent();
         if (noprefix.size() > 7) {
@@ -1419,9 +1423,11 @@ update_shader_vertex_arrays(ShaderContext *prev, bool force) {
       }
       GLint p = _glsl_parameter_map[bind._id._seqno];
 
+      // Don't apply vertex colors if they are disabled with a ColorAttrib.
       int num_elements, element_stride, divisor;
       bool normalized;
-      if (_glgsg->_data_reader->get_array_info(name, array_reader,
+      if ((p != _color_attrib_index || _glgsg->_vertex_colors_enabled) &&
+          _glgsg->_data_reader->get_array_info(name, array_reader,
                                                num_values, numeric_type,
                                                normalized, start, stride, divisor,
                                                num_elements, element_stride)) {
@@ -1463,6 +1469,14 @@ update_shader_vertex_arrays(ShaderContext *prev, bool force) {
         for (int i = 0; i < bind._elements; ++i) {
           _glgsg->_glDisableVertexAttribArray(p + i);
         }
+        if (p == _color_attrib_index) {
+          // Vertex colors are disabled or not present.  Apply flat color.
+#if defined(STDFLOAT_DOUBLE) && !defined(OPENGLES)
+          _glgsg->_glVertexAttrib4dv(p, _glgsg->_scene_graph_color.get_data());
+#else
+          _glgsg->_glVertexAttrib4fv(p, _glgsg->_scene_graph_color.get_data());
+#endif
+        }
       }
     }
   }
diff --git a/panda/src/glstuff/glShaderContext_src.h b/panda/src/glstuff/glShaderContext_src.h
index e2a9aadc9d..f9ca285572 100644
--- a/panda/src/glstuff/glShaderContext_src.h
+++ b/panda/src/glstuff/glShaderContext_src.h
@@ -65,6 +65,7 @@ private:
   //typedef pvector<ParamContext> ParamContexts;
   //ParamContexts _params;
 
+  GLint _color_attrib_index;
   pvector<GLint> _glsl_parameter_map;
   pmap<GLint, GLuint64> _glsl_uniform_handles;